It is desirable to produce ethylene/α-olefin compositions of controlled molecular weight distribution in a cost-effective manner. In particular ethylene/α-olefin compositions having a multi-modal (two or more modes wherein the case of two may interchangeably be referred to as bimodal or multi-modal) molecular weight composition distribution are often desirable for some applications, for example, pipes for natural gas, sewers, mining, etc. Also, some applications may require compositions wherein a low molecular weight portion of said ethylene/α-olefin interpolymer composition has a higher density than a high molecular weight portion of said ethylene/α-olefin interpolymer composition. Unfortunately, to date the available processes do not effectively and efficiently control the distribution or result in compositions with the desired density and molecular weight combinations.
New processes have been discovered which result in effective control of molecular weight distribution. Advantageously, the inventive processes may be designed to result in compositions wherein a low molecular weight portion of said ethylene/α-olefin interpolymer composition has a higher density than a high molecular weight portion of said ethylene/α-olefin interpolymer composition. Also, the ethylene/α-olefin interpolymer composition may be produced in a single polymerization reactor and/or using a single catalyst. Novel compositions often may result from the aforementioned processes. Said novel compositions comprise an ethylene/alpha-olefin interpolymer composition with a multi-modal molecular weight distribution and one or more molecules having a gram molecular weight equal to about ((the molecular weight of an aryl or hydrocarbyl-ligand of a pre-catalyst)+28+14*X), wherein X represents an integer from zero to 10, preferably zero to 8.